Reapply r51857 to start building chromoting plugin. Update for ppapi changes.

remoting/client/chromoting_client.h

Index: remoting/client/chromoting_client.h
diff --git a/remoting/client/chromoting_client.h b/remoting/client/chromoting_client.h
index 587f1fb190c07c5085246a445f86520eff31d1f5..50cc0dc86b2273b126114f7f42ceb004d17a5bf3 100644
--- a/remoting/client/chromoting_client.h
+++ b/remoting/client/chromoting_client.h
@@ -28,6 +28,10 @@ class ChromotingClient : public HostConnection::HostEventCallback {
 
   // Sets the viewport to do display.  The viewport may be larger and/or
   // smaller than the actual image background being displayed.
+  //
+  // TODO(ajwong): This doesn't make sense to have here.  We're going to have
+  // threading isseus since pepper view needs to be called from the main pepper
+  // thread synchronously really.
   virtual void SetViewport(int x, int y, int width, int height);
 
   // HostConnection::HostEventCallback implementation.